Conventionally known resist materials are generally polymeric materials capable of forming amorphous thin film. For example, a solution of a polymeric resist material, such as polymethyl methacrylate, polyhydroxystyrene having an acid-dissociating group and polyalkyl methacrylate, is applied on a substrate to form a thin resist film, which is then irradiated with ultraviolet ray, far ultraviolet ray, electron beam, extreme ultraviolet ray (EUV), X-ray, etc., to form line patterns having a line width of about 45 to 100 nm.
The polymeric resists generally have a molecular weight as large as about 10,000 to 100,000 and a broad molecular weight distribution. Therefore, in a lithographic fine process using the polymeric resist, the surface of the fine patterns is roughened, thereby making it difficult to control the dimension of patterns and reducing the product yield. Thus, the conventional lithographic techniques using the known polymeric resist materials have limitations in fine processing. To produce finer patterns, various low-molecular resist materials have been proposed.
For example, Patent Documents 1 and 2 propose alkali-developable negative-type radiation-sensitive compositions mainly comprising a low-molecular, polynuclear polyphenol compound. However, the profile of the obtained resist pattern is poor because of insufficient heat resistance.
As other low-molecular resist materials, Patent Document 1 and Non-Patent Document 1 propose alkali-developable negative-type radiation-sensitive compositions mainly comprising a low-molecular cyclic polyphenol compound. The proposed low-molecular cyclic polyphenol compounds have been expected to provide resist patterns with high resolution and small roughness because of their small molecular size. Since the low-molecular cyclic polyphenol compound has a rigid cyclic structure, it exhibits a high heat resistance, considering its low molecular weight.
However, the low-molecular cyclic polyphenol compound now available is less soluble in a safety solvent used in the semiconductor production process, low in the sensitivity, and provides a resist pattern with a poor profile. Therefore, the improvement of the low-molecular cyclic polyphenol compound has been demanded.    Patent Document 1: JP 2005-326838A    Patent Document 2: JP 2008-145539A    Patent Document 3: JP 2009-173623A    Non-Patent Document 1: T. Nakayama, M. Nomura, K. Haga, M. Ueda: Bull. Chem. Soc. Jpn., 71, 2979 (1998)